Hi Vitalik,
Respectfully I would recommend investigating DigiByte rather than Bitcoin Cash.
Our RPC calls are almost 1:1 as we are based also on the Bitcoin Core codebase and regularly maintain feature parity with upstream. We are far more secure than Bitcoin Cash though against any form of longer chain re-org thanks to our MultiAlgo PoW and MultiShield difficulty adjustment. We also solve your issue of 10 min blocks by being 40X faster than Bitcoin.
I’ve gone into it a little more in detail here, but I would welcome any feedback on this amendment to your proposal.
Sincerely
Josiah
On behalf of the DigiByte blockchain